Microfluidic devices and systems are gaining wide acceptance as alternatives to conventional analytical tools in research and development laboratories in both academia and industry. This acceptance has been fueled by rapid progress in this technology over the last several years.
The rapid progress in this field can best be illustrated by analogy to corresponding developments in the field of microelectronics. In the field of chemical analysis, as in microelectronics, there is a considerable need for integration of existing stationary laboratory installations into portable systems and thus a need for miniaturization. A survey of the most recent developments in the field of microchip technology can be found in a collection of the relevant technical literature, edited by A. van den Berg and P. Bergveld, under the title of “Micro Total Analysis Systems,” published by Kluwer Academic Publishers, Netherlands, 1995. The starting point for these developments was the already established method of “capillary electrophoresis”. In this context, efforts have already been made to implement electrophoresis on a planar glass micro-structure.
Microfluidic technologies have begun to gain acceptance as commercial research products, with the introduction of the Agilent 2100 Bioanalyzer and Caliper LabChip® microfluidic systems. With the advent of such commercial products, it becomes more important that users be allowed more flexibility and value for their research money, allowing broader applicability of these systems. The present invention is directed to meeting these and a variety of other needs.
In an article which is reproduced in the above-mentioned collection of relevant technical literature by Andreas Manz et al, the above-mentioned backgrounds are extensively described. Manz et al. have already produced a microchip consisting of a layering system of individual substrates, by means of which three-dimensional material transport was also possible.
Through production of a micro-laboratory system on a glass substrate, the above-mentioned article also described systems which utilized a silicon-based micro-structure. On this basis, integrated enzyme reactors, for example for a glucose test, micro-reactors for immunoassays and miniaturized reaction vessels for a rapid DNA testing have allegedly been carried out by means of the polymerase chain reaction method.
A microchip laboratory system of the above type has also been described in U.S. Pat. No. 5,858,195, in which the corresponding materials are transported through a system of inter-connected conduits, which are integrated on a microchip. The transport of these materials within these conduits can, in this context, be precisely controlled by means of electrical fields which are connected along these transport conduits. On the basis of the correspondingly enabled high-precision control of material transport and the very precise facility for metering of the transported bodies of material, it is possible to achieve precise mixing, separation and/or chemical or physicochemical reactions with regard to the desired stoichiometrics. In this laboratory system, furthermore, the conduits envisaged in integrated construction also exhibit a wide range of material reservoirs which contain the materials required for chemical analysis or synthesis. Transport of materials out of these reservoirs along the conduits also takes place by means of electrical potential differences. Materials transported along the conduits thus come into contact with different chemical or physical environments, which then enable the necessary chemical or physicochemical reactions between the respective materials. In particular, the devices described typically include one or several junctions between transport conduits, at which the inter-mixing of materials takes place. By means of simultaneous application of different electrical potentials at various material reservoirs, it is possible to control the volumetric flows of the various materials by means of one or several junctions. Thus, precise stoichiometric metering is possible purely on the basis of the connected electrical potential.
By means of the above-mentioned technology, it is possible to perform complete chemical or biochemical experiments using microchips tailor-made for the corresponding application. In accordance with the present invention, it is typically useful for the chips in the measurement system to be easily interchangeable and that the measurement structure be easily adapted to various microchip layouts. In the context of electrokinetically driven applications, this adaptation first typically relates to the corresponding arrangement of reservoirs and the electrical high voltages required for transportation of materials on the chip and to the corresponding application of these voltages to the microchip. For that reason, a laboratory environment of this type typically includes leading of electrodes to the corresponding contact surfaces on the microchip, and arrangements for the feeding of materials to the above-mentioned reservoirs. In this context it must particularly be taken into account that the microchips exhibit dimensions of only a few millimeters up to the order of magnitude of a centimeters, and are thus relatively difficult to handle.